Memory-saving printer driver

ABSTRACT

A memory-saving printer driver for controlling output image aspects and quality in a color printer. The memory-saving printer driver itself includes a user interface segment having a graphical display for selecting output image aspects. The graphical display includes a media type portion for selecting a desired one of a plural number “M” of different media types for printing an output image thereon, and a lookup table segment storing a plural number “N” of media-type basis color correction lookup tables for making color corrections on output images to be printed on each media type selected from the media portion. Each media-type basis color correction lookup table of the plural number “N” is mapped for making corrections on each of a plural and variable number “K” of different media types of the plural number “M” having a common hue angle, wherein “K” is one of a series of subsets of the plural number “M”. The result is the plural number “N” that is less than the plural number “M”, and significant savings in lookup table storage memory.

This application is a continuation-in-part of application Ser. No.08/961,081, filed Oct. 30, 1997.

FIELD OF THE INVENTION

This invention relates generally to color printing, and moreparticularly to a memory-saving printer driver along with a colorprinter and printing system including same.

BACKGROUND OF THE INVENTION

Liquid ink printers of the type frequently referred to as continuousstream or as drop-on-demand, such as piezoelectric, acoustic, phasechange wax-based or thermal, have at least one printhead from whichdroplets of ink are directed towards a recording sheet. Within theprinthead, the ink is contained in a plurality of channels. Power pulsescause the droplets of ink to be expelled as required from orifices ornozzles at the end of the channels.

In a thermal ink-jet printer, the power pulses are usually produced byresistors, each located in a respective one of the channels, which areindividually addressable to heat and vaporize ink in the channels. Asvoltage is applied across a selected resistor, a vapor bubble grows inthe associated channel and initially bulges from the channel orificefollowed by collapse of the bubble. The ink within the channel thenretracts and separates from the bulging ink thereby forming a dropletmoving in a direction away from the channel orifice and towards therecording medium whereupon hitting the recording medium a dot or spot ofink is deposited. The channel is then refilled by capillary action,which, in turn, draws ink from a supply container of liquid ink.Operation of a thermal ink-jet printer is described in, for example,U.S. Pat. No. 4,849,774.

The ink jet printhead may be incorporated into either a carriage typeprinter, a partial width array type printer, or a page-width typeprinter. The carriage type printer typically has a relatively smallprinthead containing the ink channels and nozzles. The printhead can besealingly attached to a disposable ink supply cartridge and the combinedprinthead and cartridge assembly is attached to a carriage which isreciprocated to print one swath of information (equal to the length of acolumn of nozzles), at a time, on a stationary recording medium, such aspaper or a transparency. After the swath is printed, the paper isstepped a distance equal to the height of the printed swath or a portionthereof, so that the next printed swath is contiguous or overlappingtherewith. This procedure is repeated until the entire page is printed.In contrast, the page width printer includes a stationary printheadhaving a length sufficient to print across the width or length of asheet of recording medium at a time. The recording medium is continuallymoved past the page width printhead in a direction substantially normalto the printhead length and at a constant or varying speed during theprinting process. A page width ink-jet printer is described, forinstance, in U.S. Pat. No. 5,192,959.

Printers typically print color and/or monochrome images received from animage output device such as a personal computer, a scanner, or aworkstation. The color images printed are produced by printing withseveral colored inks or colorants of different colors at a time. Thecolor of the ink and amount of ink deposited by the printer isdetermined according to image information received from a documentcreator such as a scanner or a computer workstation. The documentcreator provides an image defined in colorimetric terms, typicallydigital in nature R, G, B. Commonly this description may be part of aPage Description Language (PDL) file describing the document. In thecase of computer generated images, colors defined by the user at a userinterface of a workstation can be defined initially in a color space oftristimulus values. These colors are defined independently of anyparticular device, and accordingly reference is made to the informationas being “device independent”.

The printer, on the other hand, often has an output which can be definedas existing in a color space called CMYK (cyan-magenta-yellow-key orblack) which is uniquely defined for the printer by its capabilities andcolorants as well as the media upon which the printer deposits ink.Printers operate by the addition of overlapping multiple layers of inkor colorant in layers to a page or by the adjacent deposition ofcolorants. The response of the printer tends to be relativelynon-linear. These colors are defined for a particular device, andaccordingly reference is made to the information as being “devicedependent”. Thus, while a printer receives information in a deviceindependent color space, the information must be converted to print in adevice dependent color space, which reflects a possible range of colorsof the printer, and secondly, printing of that image with a colorprinter in accordance with the colors defined by the scanner or computergenerated image.

The perceived color of the image is determined not only by the relativeamounts of each colorant put down on the recording medium, but also bythe order in which the colorants are printed and the media type.Consequently, there are a multitude of variables which affects a finalprinted image. To accurately reproduce an original image, therefore,requires a transformation from a device independent color space to amultitude of device dependent color spaces, each one being determined,at least in part by, the combined effects of colorant, image density,media type, and print speed.

Various color printing systems and methods for printing color images ona recording medium are illustrated and described in the followingdisclosures which may be relevant to certain aspects of the presentinvention.

U.S. Pat. No. 4,275,413 to Sakamoto et al. describes a linearinterpolating method and apparatus for color signals in a memory of apicture reproducing machine such as a color scanner, a color facsimileproducer, or the like. The linear interpolating method for signals inthe memory is used for color correction of pictures in the reproducingmachine.

U.S. Pat. No. 5,664,072 to Ueda et al. describes a color conversiondevice wherein color value data including data for outputting colorimages inputted to a CPU. A color conversion means may preferablyconvert the set of input-color data into the set of print control data,while correcting the distortion in the uniform color space in regards tohuman visual sense.

“Digital Computation of Dot Areas in a Colour Scanner”, pages 93-96,Korman and Yule, Proceedings of the Eleventh International Conference ofPrinting Research Institute, Canandaigua, N.Y., 1971, describes a methodof computing the dot areas required for accurate colour reproductionsuitable for use in a color scanner with a digital computer.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there isprovided a memory-saving printer driver for controlling output imageaspects and quality in a color printer. The memory-saving printer driveritself includes a User Interface segment having a graphical display forselecting output image aspects. The graphical display includes a mediatype portion for selecting a desired one of a first plural number “M” ofdifferent media types for printing an output image thereon, and a lookuptable segment storing a second plural number “N” of media-type basiscolor correction lookup tables for making color corrections on outputimages to be printed on each media type selected from the media portion.Each media-type basis color correction lookup table of the second pluralnumber “N” is mapped for making corrections on each of a third pluraland variable number “K” of different media types of the first pluralnumber “M”, wherein “K” is one of a series of subsets of the firstplural number “M”, thereby resulting in the second plural number “N”being less than the first plural number “M”, and in significant savingsin lookup table storage memory.

In accordance with another aspect of the present invention, there isprovided a color printer including a printhead for printing color imageson a selected medium from the plurality of different media types, andmemory-saving printer driver for controlling output image aspects andquality in the color printer. The memory-saving printer driver itselfincludes a User Interface segment having a graphical display forselecting output image aspects. The graphical display includes a mediatype portion for selecting a desired one of a first plural number “M” ofdifferent media types for printing an output image thereon, and a lookuptable segment storing a second plural number “N” of media-type basiscolor correction lookup tables for making color corrections on outputimages to be printed on each media type selected from the media portion.Each media-type basis color correction lookup table of the second pluralnumber “N” is mapped for making corrections on each of a third pluraland variable number “K” of different media types of the first pluralnumber “M”, wherein “K” is one of a series of subsets of the firstplural number “M”, thereby resulting in the second plural number “N”being less than the first plural number “M”, and in significant savingsin lookup table storage memory.

In accordance with yet another aspect of the present invention, there isprovided a color printing system for printing quality color images on amedium selected from a plurality of different media types. The colorprinting system includes a color document source; a color printerincluding a printhead for printing color images on a selected mediumfrom the plurality of different media types, and memory-saving printerdriver for controlling output image aspects and quality in the colorprinter. The memory-saving printer driver itself includes a UserInterface segment having a graphical display for selecting output imageaspects. The graphical display includes a media type portion forselecting a desired one of a first plural number “M” of different mediatypes for printing an output image thereon, and a lookup table segmentstoring a second plural number “N” of media-type basis color correctionlookup tables for making color corrections on output images to beprinted on each media type selected from the media portion. Eachmedia-type basis color correction lookup table of the second pluralnumber “N” is mapped for making corrections on each of a third pluraland variable number “K” of different media types of the first pluralnumber “M”, wherein “K” is one of a series of subsets of the firstplural number “M”, thereby resulting in the second plural number “N”being less than the first plural number “M”, and in significant savingsin lookup table storage memory.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of a color ink jet printing systemincorporating printer and driver of the present invention;

FIG. 2. illustrates a schematic block diagram illustrating a method ofgenerating a memory-saving printer driver having a minimized number ofcolor correction lookup tables, in accordance with the presentinvention;

FIG. 3. illustrates graphically a chromaticity diagram showing hue linesand dynamic color range in CIE L*ab space for a plural number ofdifferent media types;

FIG. 4 illustrates graphically lightness change for the different mediatypes of FIG. 3;

FIG. 5 illustrates a schematic circuit diagram of the printer driver ofthe present invention including a User Interface segment and a minimizednumber of color correction lookup tables segment; and

FIG. 6 illustrates a detail of the User Interface of FIG. 5 for use inthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

While the present invention will be described in connection with apreferred embodiment thereof, it will be understood that it is notintended to limit the invention to that embodiment. On the contrary, itis intended to cover all alternatives, modifications, and equivalents asmay be included within the spirit and scope of the invention as definedby the appended claims.

FIG. 1 illustrates a perspective view of a color printing systemincluding a color printer such as a color thermal ink jet printer 10.Printer 10 is exemplary only. The invention can be practiced in othertypes of thermal ink jet printers, as well as other reproduction devicesincluding liquid ink printers driven by signals from a document source,such as a document raster input scanner or a personal computer 11.Printer 10 includes four ink jet ink containers 12, 14, 16, and 18mounted in a print cartridge 19 on a carriage 20 supported by carriagerails 22. The carriage rails 22 are supported by a frame 24 of the inkjet printer 10. The printhead cartridge, which comprises the inkcontainers, contain ink for supply to one or more thermal ink jetprintheads 26 which selectively expel droplets of ink under control ofelectrical signals received from a controller (not shown) of the printer10 through an electrical cable 27. The printhead 26 contains a pluralityof ink channels which carry ink from one or more of the ink containers12, 14, 16, and 18 to respective ink ejecting orifices or nozzles of theprinthead 26.

When printing, the carriage 20 reciprocates or scans back and forthalong the carriage rails 22 in the direction of an arrow 28. As theprinthead 26 reciprocates back and forth across a recording medium 30,fed from an input stack 32 containing, for instance, sheets of paper ortransparencies, droplets of ink are expelled from selected ones of theprinthead nozzles towards the recording medium 30. The ink ejectingorifices or nozzles are typically arranged in a linear arraysubstantially perpendicular to the scanning direction 28 andconsequently images are created line by line in multiple swaths of theprinthead. In page width printers a single line of information crossessubstantially the entire width or length of the recording medium.

When printing in color, such a linear array can be segmented such thatsegments of the array deposit different colors of ink to complete acolor image. It is also possible that each of the ink tanks be connectedto or include an individual linear nozzle array such that the printerincludes four linear arrays, one for each ink. Combinations of segmentedarrays and individual arrays are also possible. During each pass of thecarriage 20, the recording medium 30 is held in a stationary position.At the end of each pass, the recording medium is stepped in thedirection of an arrow 34. For a more detailed explanation of theprinthead and printing thereby refer to U.S. Pat. No. 4,571,599 and U.S.Pat. No. Re. 32,572, the relevant portions of which are incorporatedherein by reference.

The single recording sheet or medium 30 is fed from the input stackthrough the printer along a path defined by a curved platen 36 and aguide member 38. The sheet 30 is driven along the path by a transportroller 40 as is understood by those skilled in the art or, for instance,as illustrated in U.S. Pat. No. 5,534,902, herein incorporated byreference. As the recording medium 30 exits the slot between the platen36 and guide member 38, the sheet 30 is caused to reverse bow such thatthe sheet is supported by the platen 36 at a flat portion thereof forprinting by the printheads 26.

To print color images received from a document source or creator, suchas the personal computer 11, the image must be converted from an imagedefined in colorimetric terms, R, G and B electronic signals, which aretypically digital in nature, to an output which is typically defined asexisting in a color space of CMY and K electronic signals. To make sucha conversion, the original color space must be transformed to theprinter color space such that the resulting printed output reproducesthe original image in a desired fashion.

FIG. 2 illustrates one aspect of the present invention for generating amemory-saving printer driver including a minimized number of colorcorrection lookup tables. In order to convert from one color space toanother, a calibration signal generator 50 develops a number ofcalibration signals for causing a printer 52 to generate a plurality ofcolor calibration test sheets 54, 56, 58, 60, 62, and 64. Each of thecalibration test sheets are generated by printing a large number, on theorder of 1,000 (10 cyan densities by 10 magenta densities by 10 yellowdensities) patches of colors distributed throughout printer color spacefor each of a plurality of media types which will be used in the printerof FIG. 1. These media types include plain paper, premium coated paper,transparency, high resolution paper, high resolution glossy paper, andtransfer media. Other CMY combinations of interest, for instance, skintones, preferred graphics tones, or other memory colors may also beincluded.

Once each of the color calibration test sheets has been completed, thecolors of each of the patches of colors within a single test sheet aremeasured, with calorimeter 66, such as a spectrophotometer or adensitometer, to determine the characteristics of the colors generatedon the test sheets in terms of R, B, and G. These values are then inputinto a color range analyzer 68 which generates a graphicalrepresentation of the dynamic color range of the deposited inks for eachof the test sheets 54 through 64.

Conventionally, in order to achieve good printer output image quality,an ink jet printer conventionally included at least one color correctionlookup table (LUT) for each of the media types. It has been found,however, that in such printers the amount of memory space available forall of the lookup tables may be insufficient for all such lookup tablesdue to certain design constraints. This is particularly true when oneconsiders that while the ink characteristics create a real color gamut,the range of the desirable color attribute, such as chroma or hue, islimited by the media where each media may limit the range in a differentfashion.

In addition, chroma or hue is often manipulated in order to change theappearance of the output images depending on the type of image beingrecorded. For instance, a photographic image is typically printed with adifferent chroma or hue than a graphics image. Consequently, when oneconsiders the number of available print media in an ink jet printerenvironment as well as the variety of images and types of images beingprinted thereby, the amount of memory space required for the storage ofthe conventionally generated color correction tables becomes extremelylarge. Therefore, the present invention advantageously is directed to amemory-saving printer driver having a minimized the number of colorcorrection tables for generating quality images printed by a liquid inkprinter.

In one example, the color range analyzer 68 was used for generatingvalues for a color range plot as illustrated in chromaticity diagram ofFIG. 3. Three different media types, LX image series paper, mattedpaper, and glossy media, for example, were deposited with the standardtest patterns. The dynamic color range values were plotted and thencompared in CIE L*ab space in order to see how each primary color (RBGand CMY) shift varied for each of the different media types. The colorvalue measurements where done using X-RITE 938 spectrophotometer underilluminate D50 and 2 degree observer. The dynamic color range plot, asillustrated in FIG. 3, indicates that of the various hue lines HL1, HL2,HL3, HL4, HL5, HL6, HL7, HL8 and HL9, HL5, HL8 and HL9 for the primarycolors, CMY, are substantially common or coincident for a subset “k” ofthe “M” media types (where “k” is a variable number greater than 1).This means that these colors have substantially the same hue angle 83 oneach of these different media types. The dynamic color range plot, asillustrated in FIG. 3 also indicates that there is a small amount ofcolor shift in the secondary primary colors RGB as shown by the huelines HL1, HL3 and HL6. Three dimensional modeling was also performed.In addition, it has been found that a change in the dynamic range amongthe three media types occurred as illustrated in FIG. 4.

To further determine the impact on the maximum range of color gamut,three different color correction lookup tables were generated usingtetrahedral interpolation and normalized tone reproduction curve (TRC)techniques. Specifically, it was found that the lookup table for plainpaper included a gamut mapping problem because of limited dynamic rangewith a maximum density of approximately less than 1.2, resulting inimages looking darker and showing a loss of detail in shadows. Based onthese results, it was found that there were cases in which the chroma orhue is substantially constant and only the dynamic ranges DR_(i) changedfor a subset “k” (FIG. 3) of the different media types “M” (FIG.6). HereDR stands for Dynamic Range; and i=1, 2, . . . , k-−1 for the subset “k”of media types lying on a common hue line, such HL5 (FIG.3). Similarsubsets “k” (FIG. 3) can be found on hue lines HL5, HL8, HL2, HL9 andHL4. In each case, the dynamic color ranges DR₁, DR₂ . . . , DR_(k−1),among the “k” different types of media on the hue line, increases fromDR₁ nearest the center “0” of the diagram to DR_(k−1) furthest away fromsuch center. The Dynamic Range DR_(i) refers to a three dimensionalcolor gamut volume. We can also describe the dynamic range using the2-Dimensional chroma diagram (FIG. 3) and the lightness diagram (FIG.4). Often the dynamic ranges for different media types can be describedas the chroma difference and lightness difference. In FIG. 3, DR₃ has abigger chroma value than DR₁. In FIG. 4, L₃* has a bigger(lower)lightness than L₁*.

Consequently, a selection was made as a function of which of the mediamaximizes the dynamic range of ink and at the same time does notsacrifice any gamut. If an obvious color shift occurs in differentmedia, however, the color output can be adjusted without changing thethree-dimensional color correction lookup table but instead by adjustingthe TRC of the color shifted. As a result, in this example, the glossypaper LUT and the matte paper LUT were applied to the image and recordedon plain paper. The print quality of both LUT's was found to be betterthan that of the plain paper LUT specifically in the dark color andshadow regions.

Thus it was found that for the subset “k” of different media types wherethere Is not much color shift, a common lookup table generated for allthe “k” media types using data from that one of the subset “k” mediatypes having the greatest dynamic color range of DR_(k−1). In orderwords, where “k” is two, as on HL4, then a common lookup table generatedusing data from the media having DR₂ (which is greater than DR₁) will beused for both media types on that hue line. Where “k” is three, a commonlookup table generated using data from the media type having a dynamiccolor range of DR₂, will be mapped and used for the DR₂ and DR₁ mediatypes. Similarly, a common lookup table using data from the DR₃ mediatype, can be mapped and used for DR₁, DR₂ and DR₃. In general therefore,each media-type basis color correction lookup table for each of theplural and variable number “K” of different media type subsets isdeveloped from color correction data for one of the plural and variablenumber “K” having a color saturation dynamic range of at least greaterthan DR₂. As such, a memory-saving printer driver can be created inaccordance with the present invention, having a minimized number “N” ofcolor correction lookup tables as above such that “N” is significantlyless than “M”. Therefore, for any given plural number “M” of differentmedia types (where different subsets “k” of the number “M” each have acommon or coincident hue line), using a common lookup table for thesubset “k” (where “k” is greater than 1), clearly minimizes the number“N” of lookup tables required, and hence reduces the amount of printeror system memory required for storing color correction lookup table.

The present apparatus and method was also compared with the L*compression technique. While there is a color shift towards yellow whenthe L* compression is applied using a plain paper lookup table on plainpaper, a glossy lookup table used on plain paper minimized saturationloss and efficiently mapped shadow regions and dark colors. Because thecolor correction tables were generated using lookup tables having alarger color range, the shadow detail and dark color information areobtained without any compression techniques. In addition to providing anefficient way to minimize the memory space in the printer driver and tosolve gamut mapping problems in the shadow region, the present methodand apparatus is useful with any printer or copier that includesdifferent color ranges for different media. Specifically, the printerthat has a small dynamic range on plain paper can be calibrated usingthe calibration design for the special media that maximizes the colorgamut dynamic range.

Returning now to FIG. 2, based upon the results of the color rangeanalyzer 68, a minimized number of lookup tables, the lookup table 70and a lookup table 72 are generated by a color space transform processor74 operating in conjunction with the calibration signal generator 50 aswould be understood by one skilled in the art.

While FIG. 2 generally illustrates the process of generating a minimizednumber of lookup tables, it has been determined that the amount of inkdeposited on each of the media as well as the desired output imagecharacteristics enters into the generation and selection of the lookuptables. For instance, it has been determined that the lookup table 70 issufficient for printing upon the transparency paper, the high resolutionpaper, and the high resolution paper (glossy) and that the lookup table72 is sufficient for printing on the plain paper, the premium coatedpaper, and the transfer media as long as a single type of image isprinted. This initial characterization of the six media into two groupsof media depends, in part, on the amount of ink necessary to bedeposited on the respective media. However, once different types ofimages are considered, for instance photographic images versus graphicimages, each of these types of images require different lookup tables.This is because in certain types of ink jet printers the end user orcustomer prefers a different look for photographs as compared to thelook for graphics. Therefore, in general, if the media require the sameamount of ink to generate an image then those types of media might sharethe same lookup table. Then a separate lookup table is generated foreach type of image. Consequently, for the present invention, two lookuptables are contemplated for each media group, one being for graphicsimages and the other being for photographic images.

FIG. 5 is a schematic block diagram illustrating a control arrangementor printer driver of the present invention suitable for use in a colorprinter such as the ink jet printer and system as illustrated in FIG. 1.The document source device or creator 11 of FIG. 1, a scanner, or acomputer work station, generates a color image defined in colorimetricterms, typically digital in nature are Rc, Gc, and Bc. Typically, thisdescription of the image may be part of a page description language filedescribing the document in device independent terms. For instance, a PDLfile is received either by the printer itself having a printer driverincluded therein or is received by a printer driver stored in a personalcomputer associated with the printer being used. Once the image has beengenerated in RGB terms, a user typically selects from a user interface80 (see also FIG. 6), also included in the printer driver, a media type,for instance, including the six previously mentioned media types as wellas an output style including a mode of either color or black and whiteand an image type such as auto (automatic), graphics, photo, or text.

In automatic mode the print driver selects the appropriate LUT fordetermined image types, while for the remaining three, the user canselect the output style. Once an output style as well as a media typehave been selected, the RGB image is converted to a CMY K image forprinting by the printer 10. Included in the printer driver are a photoportion 82 and a graphics portion 84 as well as additional portions, forinstance, a text portion (not illustrated), for performing the necessaryconversion. Assuming that the output style selected is a color image ofa photo type, then the photo portion 82 would be selected by appropriatecontrol software resident in a printer controller such as those known bythose skilled in the art. If a media type is selected from the group ofmedia group one, then a lookup table one for media group one 86 isaccessed by the printer controller and the RGB signals are processed togenerate address entries to the table 86 which stores a set ofcoefficients with which the Rc, Gc, and Bc, digital signals may beprocessed to convert them to CMY colorant signals. The values which arenot mapped maybe determined through interpolation.

There are many methods of providing a transform from device independentdata to device dependent data, with U.S. Pat. No, 4,275,413 to Sakamotodescribing one method, which itself can be varied. Once a conversationtable is established, a method of interpolation referred to asTri-Linear or cubic interpolation may also be used to calculate outputvalues from the limited set of input values.

Upon obtaining device dependent colorant signals CMY, black addition (Kplus) is performed by input to a gray component replacement table 88 theoutput of which is CMY and K. This step is also known as under colorremoval and is usually dependent upon the minimum density of the CMYsignals. Alternatively, it is possible to combine the black addition andunder color removal with the color correction process of the lookuptable one by using a three dimensional lookup table containing valuesfor all four colorants. Once the CMY and K signals have been generatedby GCR table 88, the tone or lightness is adjusted by modification witha tone reproduction curve table 90 as is known by those skilled in theart. After the application of the tone reproduction curve at the TRC 90,a Cp, Mp, Yp and Kp signal, the output of the photo adjust 82 istransmitted to a halftone processor 92 to provide half-toning whichreduces the number of bits describing the density of each pixel to anumber of levels reproducible on the printer 10. Applicable half-toningprocesses are described in, for example, U.S. Pat. No. 4,149,194 toHolladay. The printer 10 then receives the halftone CMY and K signal togenerate the final printed output at prints 94.

If a user had selected from the main menu the photo image type but hadinstead selected a media from the media group two, the printer driverwould have selected a lookup table two 96 for generating the appropriateprinted output. The processing would proceed as described previously forthe lookup table 86. If however the graphic image type had beenselected, the graphic portion 84 of the printer driver would eitherselect a lookup table 98 or a lookup table four 100 depending on thetype of media selected. For any of the lookup tables one through four,the selected lookup table provides a reasonably accurate reproduction ofthe RGB signals input thereto such that a minimized number of lookuptables have been generated while still maintaining a reasonable printquality at the print 94. Consequently, a reduced amount of memory spaceis necessary for storage of the lookup tables. It will no doubt beappreciated, that the invention can be accomplished with a hardwarelogic implementation thereof, or a software implementation on aprogrammable processing device, or a combination of hardware andsoftware.

In recapitulation, there is provided a memory-saving printer driver(FIGS. 5 and 6) for controlling output image aspects and quality in acolor printer. The memory-saving printer driver itself includes a UserInterface segment 80 having a graphical display for selecting outputimage aspects. The graphical display includes a media type portion 81for selecting a desired one of a plural number “M” of different mediatypes for printing an output image thereon, and a lookup table segment(FIG. 5) storing a plural number “N” of media-type basis colorcorrection lookup tables (86, 96, 98 and 100) for making colorcorrections on output images to be printed on each media type selectedfrom the media portion. Each media-type basis color correction lookuptable of the plural number “N” is mapped for making corrections on eachof a plural and variable number “K” (FIG. 3) of different media types ofthe plural number “M” having a common hue angle, wherein “K” is one of aseries of subsets of the plural number “M”. The result is a pluralnumber “N” that is less than the plural number “M”, and significantsavings in lookup table storage memory.

There is also provided a color printer including a printhead forprinting color images on a selected medium from the plurality ofdifferent media types, and a memory-saving printer driver (FIGS. 5 and6) for controlling output image aspects and quality in a color printer.The memory-saving printer driver itself includes a User Interfacesegment 80 having a graphical display for selecting output imageaspects. The graphical display includes a media type portion 81 forselecting a desired one of a plural number “M” of different media typesfor printing an output image thereon, and a lookup table segment (FIG.5) storing a plural number “N” of media-type basis color correctionlookup tables (86, 96, 98 and 100) for making color corrections onoutput images to be printed on each media type selected from the mediaportion. Each media-type basis color correction lookup table of theplural number “N” is mapped for making corrections on each of a pluraland variable number “K” (FIG. 3) of different media types of the pluralnumber “M” having a common hue angle, wherein “K” is one of a series ofsubsets of the plural number “M”. The result is a plural number “N” thatis less than the plural number “M”, and significant savings in lookuptable storage memory.

There is further provided, a color printing system for printing qualitycolor images on a medium selected from a plurality “M” of differentmedia types. The color printing system includes a color document source11; a color printer 10 including a printhead 19 for printing colorimages on a selected medium from the plurality of different media types,and a memory-saving printer driver (FIGS. 5 and 6) for controllingoutput image aspects and quality in a color printer. The memory-savingprinter driver itself includes a User Interface segment 80 having agraphical display for selecting output image aspects. The graphicaldisplay includes a media type portion 81 for selecting a desired one ofa plural number “M” of different media types for printing an outputimage thereon, and a lookup table segment (FIG. 5) storing a pluralnumber “N” of media-type basis color correction lookup tables (86, 96,98 and 100) for making color corrections on output images to be printedon each media type selected from the media portion. Each media-typebasis color correction lookup table of the plural number “N” is mappedfor making corrections on each of a plural and variable number “K” (FIG.3) of different media types of the plural number “M” having a common hueangle, wherein “K” is one of a series of subsets of the plural number“M”. The result is a plural number “N” that is less than the pluralnumber “M”, and significant savings in lookup table storage memory.

While the present invention has been described with respect to aspecific embodiment thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart. Accordingly, it is intended to embrace all such alternatives,modifications, and variations that fall within the spirit and broadscope of the appended claims.

What is claimed is:
 1. A memory-saving printer driver for controllingoutput image aspects and quality in a color printer, the memory-savingprinter driver comprising: (a) a user Interface segment comprising agraphical display for selecting output image aspects, said graphicaldisplay having a media type portion for selecting a desired one of aplural number “M” of different media types for printing an output imagethereon; and (b) a lookup table segment storing a plural number “N” ofmedia-type basis color correction lookup tables for making colorcorrections on output images to be printed on each media type selectedfrom said media type portion, each media-type basis color correctionlookup table of said plural number “N” thereof being mapped for makingcorrections on each of a plural and variable number “K” of differentmedia types of said plural number “M”, wherein “K” is one of a series ofsubsets of said plural number “M”, thereby resulting in said pluralnumber “N” being less than said plural number “M”, and in significantsavings in lookup table storage memory.
 2. The memory-saving printerdriver of claim 1, wherein different media types of each one of saidseries of said plural and variable number “K” have (i) a substantiallycommon hue line as graphed on a two-dimensional color chromaticitydiagram for a given primary color and (ii) different color saturationdynamic ranges DR_(i) (where i=1, 2, . . . , k−1), increasing from DR₁,DR₂, to DR_(K−1) and lying substantially on said substantially commonhue line.
 3. The memory-saving printer driver of claim 2, wherein saideach media-type basis color correction lookup table for each said pluraland variable number “K” of different media types is developed from colorcorrection data for one of said plural and variable number “K” having acolor saturation dynamic range at least greater than said DR₂.
 4. Aprinter for printing quality color images on different media types, theprinter comprising: (a) a printhead assembly for printing quality colorimages on different media types; and (b) a memory-saving printer driverfor controlling output image aspects and quality in the printer, thememo-saving printer driver comprising: (i) a user Interface segmentcomprising a graphical display for selecting output image aspects, saidgraphical display having a media type portion for selecting a desiredone of a plural number “M” of different media types for printing anoutput image thereon; and (ii) a lookup table segment storing a pluralnumber “N” of media-type basis color correction lookup tables for makingcolor corrections on output images to be printed on each media typeselected from said media type portion, each media type basis colorcorrection lookup table of said plural number “N” being mapped formaking corrections on each of a plural and variable number “K” ofdifferent media types of said plural number “M”, wherein “K” is one of aseries of subsets of said plural number “M” thereby resulting in saidplural number “N” being less than said plural number “M”, and insignificant savings in lookup table storage memory.
 5. The printer ofclaim 4, wherein different media types of each one of said series ofsaid plural and variable number “K” have (i) a substantially common hueline as graphed on a two-dimensional color chromaticity diagram for agiven primary color and (ii) different color saturation dynamic rangesDR_(i) (where i=1, 2, . . . , k−1), increasing from DR₁, DR₂, toDR_(K−1) and lying substantially on said substantially common hue line.6. The printer of claim 5, wherein said each media type basis colorcorrection lookup table for each said plural and variable number “K” ofdifferent media types is developed from color correction data for one ofsaid plural and variable number “K” having a color saturation dynamicrange at least greater than said DR₂.
 7. A color printing system forprinting quality color Images on a medium selected from a plurality ofdifferent media types, the color printing system comprising: (a) a colordocument source; (b) a color printer including a printhead for printingcolor images on the medium; and (c) a memory-saving printer driver forcontrolling output image aspects and quality in the color printer, thememory-saving printer driver comprising: (i) a user interface segmentcomprising a graphical display for selecting output image aspects, saidgraphical display having a media type portion for selecting a desiredone of a plural number “M” of different media types for printing anoutput image thereon; and (ii) a lookup table segment storing a pluralnumber “N” of media-type basis color correction lookup tables for makingcolor corrections on output images to be printed on each media typeselected from said media type portion, each media type basis colorcorrection lookup table of said plural number “N” being mapped formaking corrections on each of a plural and variable number “K” ofdifferent media types of said plural number “M”, wherein “K” is one of aseries of subsets of said plural number “M” thereby resulting in saidplural number “N” being less than said plural number “M”, and insignificant savings in lookup table storage memory.
 8. The colorprinting system of claim 7, wherein said document source is a personalcomputer.
 9. The color printing system of claim 8, wherein saidmemory-saving printer driver is stored in said personal computer. 10.The color printing system of claim 8, wherein said memory-saving printdriver includes two tone reproduction curve lookup tables, each of saidtone reproduction curve lookup tables being selectable as a function ofa selection of one of the plurality of different media types.
 11. Thecolor printing system of claim 8, wherein said user interface segmentincludes an image type selector portion for selecting one of a pluralityof different image types.
 12. The color printing system of claim 11,wherein said plural number “N” of said color correction lookup tablesIncludes a first image type color correction lookup table and a secondimage type color correction lookup table, each being selectable as afunction of a selection of one of the plurality of different media typesand as a function of the selection of one of the plurality of differentimage types.
 13. The color printing system of claim 11, wherein saidimage type selector portion includes a photographic image type selectionand a graphics image type selection.